The present invention is relates generally to apparatus for attaching a terminal to a wire by crimping the terminal onto the wire. It relates in particular to a dual action pneumo-hydraulically driven apparatus wherein pneumatic pressure is converted to hydraulic pressure in sequential stages for operating the apparatus.
A common operation in building an electronic circuit is crimping a terminal onto a wire for connecting the wire in the circuit. The terminal typically includes a circuit connector portion for attaching the terminal to the circuit, and a crushable or crimpable portion for attaching the terminal to the wire. The crushable portion of the terminal is usually in the form of an open-ended cylinder with a slot extending completely along the length of the cylinder. The cylinder has a diameter slightly greater than the wire.
The wire is first inserted into the cylinder, and the cylinder is then crushed or crimped onto the wire. This crushing or crimping operation is usually carried out by circuit builders using hand-held, hand-operated crimping pliers. The crimping pliers have jaws including crimping dies configured to crimp a particular size and form of terminal. Frequently, a circuit builder holds a terminal, with the crimpable portion thereof in the dies. The terminal is held using a light pressure sufficient to positively grip the terminal but not sufficient to crimp the crimpable portion of the terminal. The circuit builder then inserts the wire into the crimpable portion of the terminal, and finally closes the plier jaws with sufficient force to crush or crimp the terminal onto the wire. Constant repetition of this operation can lead to a circuit builder developing carpal tunnel syndrome, arthritis or the like. This, in turn, may lead to at least temporary and even to permanent loss of employment for the circuit builder.
Certain types of power apparatus, hydraulic or pneumatic, has been developed to perform crimping operations. Commercially available hydraulic apparatus however is usually bulky, and operates in a fixed position on a workbench. Work to be crimped must thus be taken to the apparatus. A circuit builder usually finds this awkward and restrictive. Further, hydraulic and pneumatic apparatus usually operates in a single crimping or crushing stroke of jaws and dies. This requires that a builder manually retain a terminal on a wire until the crimping stroke is completed. This requires more skill and judgement than holding a terminal in pliers while inserting a wire therein. Further there is a risk that a builder's fingers may be caught in the crimping jaws during the crimping stroke.
Because of the aforementioned problems, prior art power crimping apparatus has not been widely accepted in the circuit building industry. Circuit builders are usually willing to accept the physical effort required to operate manual crimping pliers, together with the attended carpal tunnel syndrome and like risks, in return for relative convenience and efficiency of use.
Clearly there is a need for power crimping apparatus which a circuit builder may use in a similar manner to manual crimping pliers. It is believed that were such apparatus commercially available it would be accepted enthusiastically, and widely used.